We propose to investigate effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the motor (central and peripheral) system in several species of rodents by means of a broadbased, multidisciplinary approach involving behavior, neurochemistry, neurophysiology, and neuropathology. We will screen several species of laboratory rodents for neurotoxic effects of TCDD to develop an appropriate animal model or to rule out neurotoxicity of TCDD; we will assess whether TCDD alters the ability of the neuromuscular system to repair itself following injury, and whether traumatic damage to the neuromuscular system increases its sensitivity to TCDD; and, we will investigate mechanisms of neurotoxic action of TCDD on the central nervous system and neuromuscular system in a susceptible rodent species. The results of these studies may be expected to contribute valuable information concerning this potentially major public health hazard.